Subcellular distribution of aluminium in wheat roots.

At the sublethal and lethal concentration of Al in the medium total Al content in root tips and in the nuclear, mitochondrial and cytosol fractions was 5-7 times higher in the Al-tolerant than in the Al-sensitive wheat genotype. This contradicts the "avoidance" type of tolerance mechanism. At the sublethal Al concentration about 30% of Al was accumulated in nuclei and 10% in mitochondria in roots of the Al-tolerant genotype whereas only 10% of total Al was found in nuclei and 20% in mitochondria of the Al-sensitive genotype. A significant shift of Al from cytosol to nuclei was observed in both genotypes at the Al concentration lethal for each genotype, with practically no change in relative concentration of Al in mitochondria. The assay of Al concentration in plant tissue with catechol violet is more specific and sensitive than with Eriochrome Cyanine R. Mineralization is prerequisite before any Al assay; and the wet-ashing method of Piper (cf Jones & Thurman, Plant Soil, 1957, 9, 131-141) was found more satisfactory than dry digestion.